Retardation Plate Polymer Composition UV Stability

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Solution Overview

Problem

Existing retardation plates for flat panel displays face challenges in maintaining optical performance under harsh conditions, particularly when exposed to high-intensity ultraviolet rays, as polymerizable liquid crystal compounds with reverse wavelength dispersibility can experience changes in optical characteristics leading to unsatisfactory performance.

Innovation Solution

A polymerizable liquid crystal composition comprising two types of compounds, where one exhibits a positive change and the other a negative change in retardation values upon ultraviolet irradiation, offsetting these changes to maintain stable optical performance, with a specific blending ratio to minimize changes in optical characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If high-intensity ultraviolet rays are used to increase polymerization rate, then polymerization efficiency is improved, but optical characteristics change and performance becomes unsatisfactory

Engineering Contradiction:

Improvepolymerization rateVSAvoidoptical performance stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent uses a composite material system consisting of multiple polymerizable liquid crystal compounds with different ultraviolet absorption characteristics. This composite approach allows the system to maintain stable optical performance while achieving high polymerization rates under ultraviolet irradiation, resolving the contradiction between productivity and reliability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the chemical composition parameters of the liquid crystal system by selecting compounds with specific ultraviolet absorption properties. By adjusting the composition to include compounds that do not strongly absorb at the irradiation wavelength, the system achieves both high polymerization efficiency and stable optical characteristics.

Inventive Principle:

Principle #35Parameter changes

2Duration of action of stationary object

If sufficient ultraviolet irradiation is applied to ensure complete curing, then polymerization completeness is improved, but optical characteristics change during irradiation

Engineering Contradiction:

Improvecuring completenessVSAvoidoptical characteristic stability

Core Design Contradiction:

Duration of action of stationary objectVSStability of the object's composition

Solution Approach 1:

The patent converts the potential harm of ultraviolet irradiation-induced optical changes into a benefit by selecting liquid crystal compounds whose optical characteristics remain stable during irradiation. The compounds are chosen specifically because they do not undergo significant optical property changes when exposed to ultraviolet light, allowing complete curing without performance degradation.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If reverse wavelength dispersibility is maintained for display performance, then optical performance is improved, but sensitivity to ultraviolet irradiation increases

Engineering Contradiction:

Improvedisplay performanceVSAvoidultraviolet sensitivity

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by assigning different functional roles to different compounds in the mixture. Some compounds provide the reverse wavelength dispersibility needed for display performance, while others are selected specifically for their ultraviolet resistance. This functional differentiation allows the system to maintain both display quality and ultraviolet stability.

Inventive Principle:

Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The composition ensures that the retardation plate maintains high optical performance and stability even under severe environmental conditions, with minimal changes in optical characteristics when exposed to high-intensity ultraviolet rays, effectively addressing the issue of performance degradation.

Implementation Method 1

curing is sufficiently performed by irradiation with sufficient ultraviolet rays

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Implementation Method 2

a polymerizable liquid crystal compound (A) in which a polymer of the polymerizable liquid crystal compound exhibits reverse wavelength dispersibility

Methodology Applied

Scientific EffectReverse wavelength dispersibility: Birefringence

Data Source

PatentUS11591519B2Polymerizable liquid crystal composition and retardation plate

Publication Date: 2023.02.28 SUMITOMO CHEM CO LTD

AI summary

A polymerizable liquid crystal composition containing two polymerizable liquid crystal compounds (A) and (B) is provided. A polymer of compound (A) exhibits a reverse wavelength dispersion property and the phase difference value [R(A,3000,450)] at a wavelength of 450 nm measured after irradiation in an oriented state with ultraviolet ray at 3000 mJ/cm2 varies in a positive sense relative to the phase difference value [R(A,500,450)] at a wavelength of 450 nm measured after irradiation in an oriented state with ultraviolet ray at 500 mJ/cm2. A polymer of compound (B) exhibits a reverse wavelength dispersion property and the phase difference value [R(B,3000,450)] at a wavelength of 450 nm measured after irradiation in an oriented state with ultraviolet ray at 3000 mJ/cm2 varies in a negative sense relative to the phase difference value [R(B,500,450)] at a wavelength of 450 nm measured after irradiation in an oriented state with ultraviolet ray at 500 mJ/cm2.